1. Field of the Invention
The present invention relates to a rolling-bearing/sleeve assembly and, in particular, to a rolling bearing with a sleeve used, for example, to support the end of a rotary shaft for a rotor, which forms part of a compressor, in a freely rotatable manner in an aluminum compressor housing.
2. Description of the Prior Art
Conventionally, many types of compressors, such as the vane type or the like, for example, are used as compressors for air conditioners provided in automobiles.
In this kind of equipment having a rotary shaft rotating inside a housing as in the compressor used in an air conditioner and the like, the end section of the rotary shaft must be supported in a freely rotatable manner by the housing.
For this reason, a support section with a conventional configuration of the type shown in FIG. 1 is used, so that a rotary shaft 1 is supported at one end thereof in a freely rotatable manner by a wall surface 3 of a housing 2.
Specifically, the support section is comprised of a short cylindrical outer ring 5 fitted securely in a concave receiving section 4 formed in a cylindrical shape with a bottom in the wall surface of the housing 2 and having an inner raceway 7 on the inner peripheral surface of the outer ring 5, and a plurality of roller bodies 6, 6 provided between the inner raceway 7 on the inner peripheral surface of the outer ring 5 and the outer peripheral surface of the end section of the rotary shaft.
With the support section of the configuration outlined above, the rotary shaft 1 can be freely rotatable with a light force based on a rolling movement of the roller bodies 6, 6, so that the operation of a piece of equipment such as a compressor or the like proceeds smoothly.
The following drawbacks are inherent in a conventionally-used support section with this configuration.
In recent years, there have been many examples of equipment housings fabricated from aluminum alloys to provide lighter models of various types of equipment, such as compressors and the like. However, even when the housing is fabricated of aluminum alloy, the rotary shaft 1 as well as the outer ring 5 and the roller bodies 6, 6 which make up a rolling bearing must be made of steel because of the necessity for a high degree of rigidity and resistance to wear respectively in those parts.
A comparison of the coefficients of thermal expansion of steel and the aluminum alloy shows that the coefficient of thermal expansion of aluminum is considerably greater than the coefficient of thermal expansion of steel. For this reason, when the temperature of the equipment such as the compressor or the like rises, there is a large difference in the amount of thermal expansion in the housing 2 and that in the outer ring 5.
In the case where a large difference in thermal expansion occurs between the housing 2 and the outer ring 5 from a temperature rise, a clearance is produced between the inner peripheral surface of the concave receiving section 4 formed in the housing 2 and the outer peripheral surface of the outer ring 5.
When such a clearance is produced between the inner peripheral surface of the concave receiving section 4 and the outer peripheral surface of the outer ring 5, the outer ring 5 runs roughly against the inner surface of the concave receiving section 4. As a result, during rotation the rotary shaft 1 runs eccentrically with respect to the housing 2 to a degree corresponding to the width of that clearance.
When the rotary shaft 1 runs eccentrically, the condenser or the like equipped with the rotary shaft 1 operates with a high noise level because of the sound produced by the impact between the inner peripheral surface of the concave receiving section 4 and the outer peripheral surface of the outer ring 5. Furthermore, this clearance produced between the rotating outer ring 5 and the inner peripheral surface of the cylindrical concave receiving section 4 in the compressor is the cause of lowered efficiency of the compressor or the like.
Technology intended to eliminate this type of drawback in conventional equipment has been disclosed in Japanese Patent Publications for Opposition Nos. Sho. 36-2255, Sho. 39-21584 and Sho. 40-13082, Japanese Utility Model Publications for Opposition Nos. Sho. 44-22006 and Sho. 57-53873, and Japanese Publications of Unexamined UM Application Nos. Sho. 56-131024, and Sho. 62-62023. The conventional technology outlined in these documents relates to an annular or circular ring-shaped sleeve comprising a plate spring, a synthetic resin, and an assembled body of a plate spring and rubber, or the like, installed between the housing and the outer ring of the rolling bearing.
However, in the case of a sleeve incorporating the commonly known technology outlined above, the rigidity with respect to the load in the direction of compression is inadequate, or the follow-up capability with respect to changes in the width of the clearance caused by thermal expansion is poor, therefore such a sleeve cannot necessarily provide a satisfactory performance.